The present invention relates to new and improved absorbent structures and, more particularly, to new and improved absorbent structures incorporating therein corrugated web layers.
Disposable absorbent products have been known for some time, including such products as disposable diapers, sanitary napkins, wound dressings, bandages, incontinent pads, and the like. These products incorporate an absorbent batt which is used to absorb and hold or contain body fluids. Initially in many of these products, especially diapers and sanitary napkins, the absorbent batt comprised what is termed "wadding" or plies of tissue. The wadding was disposed between an impermeable backing and a permeable facing and the plies of tissue were used to absorb and hopefully contain the liquid within the product. A diaper which utilizes such an absorbent batt is disclosed in U.S. Pat. No. Re. 26,151.
The wadding type of batt was replaced, for the most part, by an improved absorbent batt which comprises what is termed "fluffed wood pulp fibers". This absorbent batt comprises a layer of individualized wood pulp fibers with the layer having substantial thickness. A diaper which incorporates such a fluffed wood pulp absorbent batt is described in U.S. Pat. No. 2,788,003. This diaper had improved absorbent capacity and somewhat better containment than a diaper using a wadding layer. Also, the fluffed wood pulp layer is quite soft, flexible and conformable, and hence produces an improved diaper over diapers using wadding as the absorbent layer.
Though the fluffed wood pulp absorbent batts have improved capacity, the efficiency with which the capacity is used in a diaper or sanitary napkin is poor. The reason for this is that the fluid to be absorbed is generally deposited in a localized area within the absorbent batt and the ability of the fluid to move along the plane of the batt is poor. The fluid tends to follow a radial wicking path and consequently moves to the closest edge of the batt where it generally is no longer contained and the product leaks.
U.S. Pat. No. 3,017,304 discloses an absorbent product which incorporates in the product a densified paper-like layer. This paper-like layer acts as a wick, i.e., liquid which is placed on the layer tends to move rapidly along the plane of the layer. When incorporated in combination with fluffed wood pulp fiber, the resultant product uses the absorbent capacity of the fluffed wood pulp much more efficiently. Diapers which incorporate this paper-like layer combined with fluffed wood pulp are disclosed and described in U.S. Pat. Nos. 3,612,055 and 3,938,522. This concept of combining wicking ability, or a capillary skin or layer, with fluffed wood pulp fibers has gained wide acceptance in many absorbent products, including disposable diapers and sanitary napkins. Even though these products make much greater use of the capacity of the absorbent batt, they still do not totally contain the absorbed liquid. It is probable that these products will leak before the full capacity of the batt is used for absorption or at the very least before the entire liquid void by the user is absorbed. This is especially true when pressure is placed on the batt while wet. For example, a baby sitting down on a previously wetted diaper will very often cause the batt to leak.
A incontinent adult faces many problems. First, the void of an adult generally is much higher in volume than that of an infant. Second, a bulge under clothing is accepted by society for an infant, but the ambulatory adult with an incontinence problem longs for a product which is not visible through ordinary clothing. Third, the proportions and shape of the legs and torso of the adult differs considerably from those of an infant. Therefore, a mere enlargement of an infant diaper, such as that shown in U.S. Pat. No. 4,253,461, is not a satisfactory product.
In both the infant diaper and adult incontinent product marketplace, a product is needed which has a large storage capacity. For instance, shaped containers have been suggested. However, these containers have been substantially rigid, do not stay in place and are quite uncomfortable. A product with a substantially large liquid storage capacity, with an ability to move liquid away from the void zone, which is disposable, which is comfortable, and which does not show through wearing apparel is needed in the marketplace.
The present invention provides a new and improved absorbent product which provides a large storage capacity and ability to transport liquid from the void zone, which is soft and comfortable, and which can be designed so as not to be apparent through normal clothing. In addition, the new absorbent product will contain absorbed liquid even when pressure is placed upon the product during use.